Java tutorial
/* * Copyright 2017 - 2018 Anton Tananaev (anton@traccar.org) * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.traccar.protocol; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import org.traccar.BaseProtocolEncoder; import org.traccar.helper.Checksum; import org.traccar.model.Command; import java.nio.charset.StandardCharsets; public class GalileoProtocolEncoder extends BaseProtocolEncoder { private ByteBuf encodeText(String uniqueId, String text) { ByteBuf buf = Unpooled.buffer(256); buf.writeByte(0x01); buf.writeShortLE(uniqueId.length() + text.length() + 11); buf.writeByte(0x03); // imei tag buf.writeBytes(uniqueId.getBytes(StandardCharsets.US_ASCII)); buf.writeByte(0x04); // device id tag buf.writeShortLE(0); // not needed if imei provided buf.writeByte(0xE0); // index tag buf.writeIntLE(0); // index buf.writeByte(0xE1); // command text tag buf.writeByte(text.length()); buf.writeBytes(text.getBytes(StandardCharsets.US_ASCII)); buf.writeShortLE(Checksum.crc16(Checksum.CRC16_MODBUS, buf.nioBuffer(0, buf.writerIndex()))); return buf; } @Override protected Object encodeCommand(Command command) { switch (command.getType()) { case Command.TYPE_CUSTOM: return encodeText(getUniqueId(command.getDeviceId()), command.getString(Command.KEY_DATA)); case Command.TYPE_OUTPUT_CONTROL: return encodeText(getUniqueId(command.getDeviceId()), "Out " + command.getInteger(Command.KEY_INDEX) + "," + command.getString(Command.KEY_DATA)); default: return null; } } }